The present disclosure generally relates to sports substrates marked with indicia, particularly to those that are subject to impact during play, and to methods of preparing such marked sports substrates, particularly game balls, by an ink that is printed and cured.
Inks curable with ultraviolet light (“UV”) are quick-curing inks useful in continuous-type processes in which subsequent treatment of an ink-printed substrate is involved. A number of UV-curable inks are known. Typical UV-curable inks comprise acrylate- or methacrylate-functional resins, oligomers, and monomers along with a photoinitiator component that absorbs in the ultraviolet region of light. Using UV-curable ink for applying indicia to a game ball has been described, for example in Keller et al., U.S. Pat. No. 5,770,325 and Lutz, U.S. Pat. No. 6,013,330. Curing with UV light is a less than satisfactory process in that the cost of bulbs is high and their operation is energy-intensive. Further, ozone is typically generated, which presents a potential regulatory issue.
Lutz, U.S. Pat. No. 6,248,804, teaches when a combination of UV and visible light photoinitiators or when photoinitiators having an absorbance spectrum in both the UV and visible light regions are used in an ink printed on a game ball such as a golf ball, the ink is cured using both UV and visible light. This is said to ensure through-cure of the ink. However, the process has all the shortcomings of a solely UV-curing process with the additional complexity and expense of adding visible light curing.
There exists a need for a highly durable ink curable with visible light for printing indicia on surfaces of sports equipment such as a curved and dimpled surface of a golf ball, and which provides an image having good durability on a substrate subject to impact during play.